The efficacy of prophylactic treatment with DR3 activation is dependent on recipient-derived Treg. (A) TCD-BM from WT B6 mice were transplanted into lethally irradiated Balb/c recipients on day 0, and Treg-depleted T cells from B6-Foxp3DTR mice (1 × 106/animal) were injected on day 2 after transplant. For preparation of Treg-depleted T cells, DT (1 μg/animal) was administered to donors on days −2 and −1. αDR3 or isotype control Ab was injected into recipient mice on day 0. (i) Experimental scheme. GVHD score (ii) and survival curve (iii) are shown (n = 10 in TCD-BM; n = 13 in D0 isotype with Treg-depleted T cells; and n = 20 in D0 αDR3 with Treg-depleted T cells; *P < .05; **P < .01; ***P < .001; ****P < .0001). (B) TCD-BM from WT Balb/c mice were transplanted into lethally irradiated B6-Foxp3DTR mice on day 0, and T cells from Balb/c mice were injected on day 2 after transplant. For recipient-derived Treg depletion, DT was injected into recipient mice on days −2, −1, +3, and +5. αDR3 or isotype control Ab was administered to recipient mice on day 0. (i) Experimental scheme. GVHD score (ii) and survival curve (iii) are shown (n = 6 in TCD-BM + D; n = 8 in TCD-BM + T cell + DT; n = 17 in TCD-BM + T cell + D0 αDR3; and n = 12 in TCD-BM + T cell + D0 αDR3 + DT; n.s = not significant; ***P < .001; ****P < .0001).
